KR101103100B1 - Circuit arrangement with error detection for activating power semiconductor switch and associated method - Google Patents

Abstract

The present invention relates to an integrated circuit device consisting of a primary side and a secondary side, and a method thereof for driving a power switch arranged in a bridge circuit topology. The primary side includes a signal processing device and a level shifter for driving the secondary side without potential. The secondary side includes a driver stage for the signal processing device and the TOP switch. To detect the switching state of the TOP switch on the primary side, the primary side includes circuit components for detecting and evaluating the flow of current through the level shifter. The first lower limit threshold of the current through the level shifter detected at the primary side is related to the TOP switch of the bridge circuit not being turned on, and the second upper limit threshold of the current through the level shifter detected at the primary side is the bridge. It is related to that the TOP switch of the circuit is turned on.

Bridge Circuit Topology, Power Switch, Primary Side, Secondary Side, Circuit Devices, Level Shifter

Description

CIRCUIT ARRANGEMENT WITH ERROR DETECTION FOR ACTIVATING POWER SEMICONDUCTOR SWITCH AND ASSOCIATED METHOD}

1 is a diagram of a circuit arrangement according to the prior art;

2 is a diagram of a level shifter according to the prior art.

3 is an illustration of an improved circuit arrangement in accordance with the present invention.

4 illustrates the relationship between current flow through a level shifter and threshold formation;

5 is an illustration of an improved first embodiment of a level shifter for placement in a circuit arrangement in accordance with the present invention.

Figure 6 is a diagram of an improved second embodiment of a level shifter for placement in a circuit arrangement in accordance with the present invention.

<Explanation of symbols for the main parts of the drawings>

20: Primary side

30: secondary

44: level shifter

50: TOP switch

52: BOT switch

60: diode

100: circuit device

The present invention relates to a preferably integral circuit arrangement and method for driving a power switch arranged in a bridge circuit topology. Bridge devices for such power switches are known as half-phase, H-phase (or more), or three-phase bridge circuits, and single-phase half bridges represent the basic components of such power electronic circuits. In the half-bridge circuit, two power switches, that is, a first switch so-called TOP switch and a second switch so-called BOT switch, are arranged in series connection. The half bridge generally includes a connection to a direct current intermediate circuit. Normally the middle tap is connected to the load.

In the structure of a power switch that is a power semiconductor component or a power switch that is a plurality of parallel or series connected power semiconductor components, a driving circuit is required for driving the power switch. According to the prior art, such a driving circuit consists of a plurality of component circuits or functional blocks. The drive signal transmitted from the control device disposed above is processed on the first component circuit, that is, on the primary side, and finally provided to the control input of each power switch through the drive circuit, that is, on the other component, that is, on the secondary side. In the case of a half-bridge device with a high intermediate circuit voltage, for example 50 V or more, the primary side processing the control signal is separated from the secondary side in potential / electricity, because the power switch, i.e. at least the half bridge TOP switch, is constant during operation. This is because it cannot exist at a potential and separation in voltage is necessary. According to the prior art, the separation is done, for example, by transducers, optocouplers or optical waveguides. This electrical separation is done at least for the TOP switch, but also for the BOT switch in the case of high power due to the division of the ground reference potential that may be present in the switching operation.

Integrated circuit arrangements are also known for power switches of voltage class up to 600V or 1200V, omitting external electrical disconnect devices. In the case of such monolithic integrated circuits, according to the prior art, at least so-called level shifters for TOP switches are used. The electronic component and separation technique adjust the potential difference of the primary side relative to the secondary side.

In the structure of the integrated circuit device for driving the power switch described above, at least in the simplest structure for the secondary side of the TOP switch, no method of transmitting an error to the primary side is provided.

An object of the invention is preferably a monolithic integrated circuit device for a power semiconductor switch of a bridge device which enables the primary side to detect the switching state of at least one power semiconductor switch of the secondary side by simple and integral means. And it provides a method for this.

According to the invention, this object is achieved through the means of the features of claims 1 and 5 herein. Preferred embodiments are disclosed in the dependent claims.

The idea of the invention relates to a known circuit arrangement for driving a power semiconductor switch of a bridge topology consisting of a primary side component (primary side) and one secondary side component (secondary side) for each power semiconductor switch. The bridge circuit consists of a first TOP switch and a second BOT switch. They are connected according to the prior art to direct current intermediate circuits. The intermediate tap between the TOP switch and the BOT switch forms the AC output of the bridge circuit. The drive circuit arrangement includes at least one signal processing device on the primary side and at least one level shifter for driving at least one secondary side without potential. The secondary side includes at least one signal processing device and at least one driver stage for each switch.

The present invention proposes a preferably monolithic integrated circuit device for driving a power semiconductor switch, wherein an existing level shifter is used to transfer the switching state of the semiconductor switch from the secondary side to the primary side. The level shifter is used only for transmitting drive signals from the primary side to the secondary side according to the prior art. According to the invention, at least one circuit component is arranged on the primary side for detecting and evaluating current flow through at least one level shifter associated with the monitored power semiconductor switch.

The method for this is used to detect the switching state of the power semiconductor switch driven on the secondary side on the primary side. To this end, the current flow through the level shifter is evaluated on the primary side. Here, the first lower limit threshold value of the current through the level shifter detected on the primary side indicates that the switch of the bridge circuit is not turned on, while the second upper limit threshold value of the current through the level shifter detected on the primary side is Indicates that the switch of the bridge circuit is turned on.

The idea of the present invention is explained in detail by the embodiment of Figs.

When driving a power semiconductor component 50, 52, for example an insulated gate bipolar transistor (IGBT) with a non-parallel connected free wheeling diode in a circuit arrangement of a bridge topology, on the one hand, Voltage difference between the control device 10 in the form of a microcontroller 10 and the primary side 20 of the circuit arrangement, on the other hand, the secondary side 30, 32 of the circuit arrangement and the power semiconductor component 50, Due to the voltage difference between 52) a potential separation device is required. According to the prior art, various potential separation devices are known, for example transformers, optocouplers, optical waveguides or electronic components having a corresponding electric strength.

In the case where the primary side 20 and the secondary side 30 of the circuit device 100 for driving the power semiconductor switches 50 and 52 according to Fig. 1 are monolithic integrated, they are moved from the primary side 20 to the secondary side. Level shifters 44 are often used to convey control signals.

The turn-on and turn-off signals can be transmitted from the primary side 20 (low voltage side) to the secondary side 30 (high voltage side) by the potential separation component. For trouble-free operation of the power electronic system, it is of course important to be aware of the operating state of the secondary side 30 at the primary side 20, for example the specific switching states of the TOP and BOT switches.

2 shows a known topology of a monolithic integrated level shifter, wherein the level shifter has an nMOS-high voltage transistor having a blocking capability corresponding to the maximum potential difference between the primary side 20 and the secondary side 30 here. 430. The drive on the secondary side is from the primary side. As soon as the primary side 20 turns on the high voltage transistor 430, the lateral current Iq flows between the supply voltage Vs on the secondary side and the ground reference potential on the primary side 20. The current flow Iq is detected on the secondary side and converted into a signal to be processed.

The level shifter 44 is controlled via the input signal Sin. Preferably the signal is preamplified for this purpose and applied to the control input of low voltage transistor 432. As long as the low voltage transistor 432 is opened, the potential of the supply voltage Vp on the primary side is applied to the "source" of the high voltage transistor 430. Since the "gate" of the high voltage transistor 430 is similarly applied to the supply voltage Vp of the primary side 20, the high offset of the offset between the primary side and the secondary side is made in the high voltage transistor 430. When the low voltage transistor 432 is turned on, the potential at the source of the high voltage transistor 430 decreases and the lateral current Iq starts to flow. The lateral current is, of course, limited through the reduction resistor 424. Accordingly, the lateral current Iq transmits the switching signal on the primary side to the secondary side by evaluating the voltage drop across the resistor 420. In the stopped state, for the "low" input signal Sin, the circuit does not consume energy except for the neglected leakage current of the high voltage transistor 430. The signal stroke on the secondary side is limited via the zener diode 410. The zener diode 412 continuous circuit on the primary side protects the low voltage transistor 432 from the transient overvoltage load along with the resistor 424.

Due to the clamping on the secondary side and the current limitation through the reducing emitter, the lateral current Iq is changed by the offset voltage at the high voltage transistor 430 while being turned on by the pulse. Here, the drain current value with respect to the offset voltage indicates the saturation state of the high voltage transistor (see FIG. 4).

The total voltage Ug (see Fig. 4) is shown as the potential difference between the primary ground reference potential and the secondary supply voltage Vs. This therefore corresponds to the sum of the offset voltages between the primary and secondary and secondary side operating voltages.

3 shows an improved monolithic integrated circuit arrangement 100 in accordance with the present invention, which may of course be implemented in the same manner as a hybrid circuit arrangement. In the embodiment according to the present invention, the level shifter 44 is complemented by a current detector 46, a voltage detector 47, and a current limiter 48 at the primary side 20. The lateral current Iq is adjusted according to the total voltage Ug. The lateral current Iq is detected by the current detector 46 and converted into a signal usable by the voltage detector 47. The current limiter 48 is used to limit the load of the high voltage transistor to limit the current consumption of the level shifter 44.

The power semiconductor switches 50, 52 of the bridge arrangement are used in the switching operation, ie they are interacted to turn on and off. Therefore, the intermediate tap (output part) of the bridge has only two stop states. When the TOP switch 50 is turned on with the BOT switch 52 turned off, the intermediate tap is applied with approximately the intermediate circuit voltage, and the TOP switch 50 is turned off with the BOT switch 52 turned on. When applied, the intermediate tap is applied at approximately ground reference potential. Therefore, in order to detect the switching state of the TOP switch 50, the magnitude of the lateral current Iq of the level shifter 44 should be detected at the primary side 20, and the lateral current Iq is determined by the total voltage Ug. It is adjusted according to the size.

When the turn-on impulse from the primary side 20 to the secondary side 30 is transmitted through the level shifter 44, the lateral current Iq depends on the total voltage Ug. When the TOP switch 50 is turned on, the overall voltage rises. Due to the characteristics of the level shifter 44 described above, when the overall voltage rises as described above, the lateral current Iq increases. Fig. 4 shows the above relationship shown schematically in terms of the detection circuit on the primary side. Here, it is determined that the lateral current Iq is increased above the second threshold value I2, and as a result, it is evaluated that the TOP switch is turned on. In contrast, if the first threshold value I1 is not reached (less than), the TOP switch is evaluated as not being turned on. The current between the first threshold and the second threshold is the current difference that must be accurately identified in the circuit for accurate confirmation of the switching state. Accordingly, it is possible to accurately determine whether or not the secondary side switch is turned on by the transmitted turn-on signal through the lateral current Iq measuring device on the primary side.

Figure 5 shows an improved first embodiment of a level shifter 44a for placement in a circuit arrangement according to the invention. The threshold can be converted to simplify the detection of the lateral current Iq. To this end, the secondary side of the level shifter 44a may be deformed by the potential converting portion. Here, the series connection 414 of the zener diode replaces the single zener diode 410 and the parallel connected resistor 420 of FIG. The structure converts the saturation value of the lateral current Iq with respect to the total voltage Ug during operation to generate a symmetrical transfer characteristic. This means that the slope of the current-voltage change is formed on the one hand in the region of the first threshold I1 (see FIG. 4) and on the other hand the second threshold I2. Thus, advantageously, in the case of the embodiment of the level shifter 44a, the function control can be executed via another turn-on impulse even during the time when the associated switch is already assumed to be turned on. Even in this case, the evaluation unit of the lateral current Iq transmits the switching state of the TOP switch. Indirectly, by the above-mentioned transmission, a switch break due to an error state of the secondary side, for example, an under-voltage error state, may be transmitted to the primary side and transmitted to a control device disposed above.

FIG. 6 shows an improved second embodiment of a level shifter 44b for placement in a circuit arrangement according to the invention, based on the level shifter 44a according to FIG. The disadvantage of this embodiment according to Fig. 5 is that error propagation can only be initiated by the primary side and the secondary side cannot actively transmit the error to the primary side. To enable this, the series connection 414 of the zener diodes is such that the intermediate voltage transistor 434, which should have an electrical strength greater than the sum of the voltages of the zener diodes 414a, is connected in parallel to the plurality of zener diodes 414a. Is formed on the secondary side. The other Zener diodes 414b remain unaffected by the deformation. In this case, advantageously, in the case of the monolithic one-piece, in particular, the intermediate voltage transistor 434 has a smaller area of demand than the high voltage transistor 432, and thus is inherently unique through the high voltage transistor from the secondary side to the primary side. It can be integrated into the circuit arrangement technically simpler, more space-saving and more advantageous in terms of cost than with a transmission path.

In the case of the intermediate voltage transistor 434 driven by the secondary side and cut off in normal operation, the characteristics of the level shifter 44b are the same as those of the level shifter of Fig. 5, i.e., the significant lateral current Iq only in the driving stage of the level shifter. ) Flows. In case of any error, the secondary side may actively turn on the intermediate voltage transistor to start the lateral current flow. The lateral current flow is detected on the primary side and identified as an error signal from the secondary side to the primary side.

According to the present invention, preferably a monolithic integrated circuit device for a power semiconductor switch of a bridge device which enables the primary side to detect the switching state of at least one power semiconductor switch on the secondary side by simple and integral means. And a method thereof.

Claims (7)

A power semiconductor switch of a bridge topology, consisting of a primary component (primary side 20) and one secondary component (secondary side 30) for the TOP switch 50 and the BOT switch 52 of the bridge circuit ( In the monolithic integrated circuit device 100 for driving 50, 52, The primary side 20 includes at least one signal processing device and at least one associated level shifter 44 for driving at least one secondary side 30 without potentials, The secondary side 30 comprises at least one signal processing device and at least one driver stage for each switch 50, In order to detect the switching state of at least one power semiconductor switch 50, at least one circuit component 46, 47 is provided on the primary side 20 for detecting and evaluating the current flow Iq through the associated level shifter 44. , 48) is arranged. The voltage shifter 44 of claim 1, wherein the level shifter 44 includes a secondary voltage supply Vs, at least one zener diode 410, a secondary output Vo, a high voltage transistor 430, and a primary voltage supply Vp. And a low voltage transistor (432). 3. The circuit arrangement according to claim 2, wherein the level shifter (44) comprises a series connection (414) of zener diode behind the voltage supply on the secondary side. 4. The circuit arrangement according to claim 3, wherein the series connection (414a / b) of the zener diode is modified such that the intermediate voltage transistor (434) is arranged in parallel with respect to the plurality of zener diodes (414a). In the method for detecting the switching state of the power semiconductor switch 50 in the circuit device 100 according to claim 1, The current flow Iq through the level shifter 44 is evaluated by the circuit components 46, 47, 48 placed here on the primary side 20, The first lower limit threshold I1 of the current Iq through the level shifter 44 detected at the primary side 20 indicates that the switch 50 of the bridge circuit is not turned on. And the second upper limit threshold (I2) of the current (Iq) through the level shifter (44) detected at the primary side (20) indicates that the switch (50) of the bridge circuit is turned on. Method according to claim 5, characterized in that the current flow (Iq) through the level shifter (44) is detected by the current detector (46) and the voltage detector (47). Method according to claim 5, characterized in that the current limiting part (48) of the primary side (20) prevents overload of the level shifter (44).

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